Intergranular fracture in low carbon iron

The influence of grain size and temperature on twinning, yield and fracture has been examined in two low carbon irons. The evidence indicates that crack nucleation is the critical event in intergranular fracture and fracture can occur prior to general yielding or after subsequent work hardening. Twinning is not a prerequisite of intergranular failure, and the effect of impurity segregation at grain boundaries is to lower the cohesive energy of the boundaries rather than to increase the difficulty of slip propagation.